Hardfaced underreamer cutter and method of forming the same



June 15, E. w. HOLIDAY ET AL HARDFACED UNDERREAMER CUTTER AND METHOD OF FORMING THE SAME Filed Dec. 26, 1934 Patented June 16, 1936 HARDFACED UNDERREAMER CUTTER AND NIETHOD OF FORMING THE SAME Edward W. Holiday and Fred K. Blauvelt, Wichita, Kans., assignors to The Bridgeport Machine Company, Wichita, Delaware Kama, a corporation of Application December 26, 1934, SerialNo. 759,222

2 Claims.

This invention relates to new and useful improvements in methods of hardfacing cutters and to the product thereof.

It has been the practice in the manufacture of cutting tools to provide said tool with a cutting edge of hard material, such as carbides of various metals. In applying this hard material to the tool, only a comparatively thin layer of the hard ,material has been secured to the tool. Further the layer has either been applied on an inclined surface because the edgeof the tool is beveled or the hard surfacing has not been adequately braced against shearing strains. Due to the thinness of the layer and the inclined backing, there is a tendency for the hard material to spall or break on under cutting strains, thereby reducing the efficiency, as well as causing frequent resurfacing.

One object of the invention is to provide an improved method of applying a hardfacing materia'lto' a cutting tool to form a cutting edge, said material being so applied as to eliminate its spelling or breaking off from the body of said tool.

A particular object of the invention is to pro vide an improved method of hardfacing a cutting tool which consists in forming recesses or cut-out portions in stepped relation along the lower outer edge of the cutting tool, and inserting a hard material in such recesses, which are of sufficient depth to receive a substantially thick layer of said hard material whereby the life of the cutting edge is prolonged and more efficient work is done.

Another object of the invention is to form stepped recesses in the lower outer edge of a cutting tool for receiving hard material to form a cutting edge, said recesses being angular in shape and extending at substantially right angles to the vertical and horizontal planes of the material to be cut, whereby the outer cutting edge of hard material is provided with a backing to absorb the shock of the cutting operation, thereby eliminating the necessity of field dressing the tool.

A further object of the invention is to provide a cutting edge of hard metal on a cutting tool, said hard metal being of a thickness equal to the thickness of the material removed in cutting, whereby tendency of said metal to spall or break off is eliminated. A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing, in which an example of the invention is shown, and wherein:

Figure 1 is a vertical, sectional view of aportion of an underreamer' constructed in accordance with the invention,

Figure 2 is an isometric View of one of the cutters,

Figure 3 is a longitudinal sectional view of the same,

Figure 4 is an enlarged sectional view of the lower end of the cutter without the hardfacing applied thereto,

Figure 5 is a view similar to Figure 4 and having the hardfacing applied thereto, and Figure 6 is a sectional view of amodified form of the invention.

Inthe drawing, the numeral l0 designates the body of an ordinary underreamer for use in wells. The body carries a pair of retr'actible cutters H which depend therefrom and these cutters perform the actual reaming (not shown) first drills the hole A, as shown, and the underreamer is then utilized to enlarge said hole to permit the casing B to move downwardly therein or for other purposes. The lower outer edge of each cutter, as well as the bottom thereof, engages the side wall of the hole and removes material from one to two inches in thickness to enlarge said hole. This outer edge and bottom is usually provided with a facing of hard material, such as carbides of various metal, whereby the life of said cutting edge is prolonged and will perform more efiiciently. In applying this hard material to the cutter, the usual practice has been to bevel the cutting edge, as shown in Figure 6, and apply said material thereto. Due to the particular way this edge has been cut back, only a thin layer of the hard material can be applied and also since the material is secured to an inclined surface, there is a tendency for said material to spall or break off particularly at its edges under shearing strain because of the lack of any shoulder or other means to absorb the shock,

or ar.

In carrying out the improved method, the bottom of the body ll of the cutter is stepped to form shoulders l2 and I3. The shoulder l2 which is at the outer marginal portion of the cutter is of a greater width than the inner shoulder -l3 and both shoulders are fiat in a horizontal plane. An outwardly extending flange I4 is formed on the outer side of the body above the shoulder l2 and this flange has both its upper and lower end beveled, the upper bevel being at operation. The drill cutter. Thus, is applied in and enlarged provided.

It is pointed outer edge it is obvious that after this manner, a substantially thick cutting edge of hard material is the ordinary cutter will.

feature of the construction is the hard material in the ofiset An important the insertion of formed between obvious that this structure provides backing for the hard material, the cutting operation is absorbed impact of the cut the shoulders I the material 2 and I3, and

ng protected against the sudden ter with the form ation being cut.

This greatly prolongs the life of the cutter because the body ll of said cutter, rather than the may be employed in applying the hard material to said cutter.

' EDWARD W. HOLIDAY.

FRED K. BLAUVELT. 

